The present invention relates to a method and apparatus for labelling products.
Products to be sold are commonly labelled. In this regard, automatic labelling apparatus may be employed where the products are smaller and processed in large volumes. One approach in this regard is to wipe a label onto each product as its passes a labelling head. This approach, however, is only well suited for labelling products of uniform dimensions. Where products have irregular dimensions, such that the distance between a given product and the labelling head will vary, tamping labellers are typically used. U.S. Pat. No. 5,829,351 to Anderson discloses such a labeller. In Anderson, a turret carries a number of flexible pneumatic bellows about its periphery. The turret has a vacuum plenum and a positive pressure plenum. The turret rotates each bellows, consecutively, to a labelling station. A bellows normally communicates with the vacuum plenum which keeps it in a retracted position; also, due to end perforations in the bellows, the negative pressure holds a label at the end of the bellows. However, when the bellows reaches the labelling station, it is coupled to the positive pressure plenum which causes a one-way valve to block the perforations and causes the bellows to rapidly extend until it tamps a product below. The force of the tamping forms an adhesive bond between the pressure sensitive adhesive of the label and the product. Labels are fed to each bellows from a label cassette with a label web comprising serially arranged labels on a release tape. The release tape is split along a weakened centreline to release the labels.
A problem arises if products are irregularly arranged such that they do not all pass directly below the labelling station. A further difficulty faced by a tamping apparatus employing a flexible bellows is in the accurate control of tamping with the bellows. Yet another difficulty is in the synchronisation of the label web with the bellows and in the ease of reloading a label cassette. This invention seeks to address at least some of these problems.
In one aspect, a target area for a given product conveyed on a conveyor is determined relative to a frame of reference. One of a plurality of labellers fixed at different transverse positions over the conveyor, which one labeller is at a transverse position which is within the transverse extent of the target area is then activated in order to label the product. In another aspect, a labeller has a flexible bellows with an interior air diffuser. The air diffuser has a central opening facing the tamping end of the bellows and at least one side opening. This arrangement can enhance the responsiveness of the bellows. In a further aspect, a labeller has a two-sided timing belt driven by a stepper motor with a de-mountable label cassette which, when mounted, has a drive pinion meshing with the two-sided timing belt. In another aspect, a labeller has a label cassette with a driven pin wheel for moving a pin holed release tape of a label web. A ratchet tooth having a fixed relation to a pin of the pin wheel engages a pawl to set a limit for driving the label web in a label web retracting direction in order to set a start position for a label on the web. It is useful to set the label cassette at this start position when the cassette is first mounted and then occasionally thereafter in order to reduce the likelihood of label mis-feeds.
Accordingly, the present invention provides labelling apparatus for use with a conveyor for conveying products in a downstream direction, comprising: a vision system for imaging products on said conveyor; a plurality of labellers downstream of said vision system, each labeller for being fixed above said conveyor at a different transverse position over said conveyor; a processor for, responsive to an input from said vision system, selecting a labeller to label a given product and sending an activation signal to one said labeller.
According to another aspect of the invention, there is provided a method of labelling products, comprising conveying products in a downstream direction, determining a target area for a given product on the conveyor relative to a frame of reference, and activating a one of a plurality of labellers positioned above the conveyor at fixed transverse positions which one labeller is within a transverse extent of the target area. A computer readable medium is also provided to effect this method.
According to a further aspect of the present invention, there is provided a product labelling apparatus comprising: at least one flexible bellows having a retracted position and an extended tamping position; an air diffuser associated with each bellows, each air diffuser extending interiorly of an associated bellows from a base of said associated bellows toward a tamping end of said associated bellows, said each air diffuser having a central opening facing said tamping end of said associated bellows and at least one side opening facing a side of said associated bellows.
According to another aspect of the invention, there is provided a labelling apparatus comprising: an indexing turret carrying a plurality of tamping labellers; a stepper motor for stepping in synchronism with step-wise movement of said turret, said stepper motor for driving a two-sided timing belt; a releasable mount for a label web cassette; said label web cassette having a drive pinion, said drive pinion for meshingly engaging with said two-sided timing belt when said label web cassette is mounted to said releasable mount.
According to a further aspect of the invention, there is provided a labelling apparatus comprising: an indexing turret carrying a plurality of tamping labellers; a label web cassette normally driven in synchronism with said indexing turret; wherein a label web of said cassette has a pin hole between each label and wherein said label web cassette has a driven pin wheel engaging said pin holes; and a ratchet tooth fixed in relation to a pin of said pin wheel and a pawl setting a limit for driving said label web cassette in a label web retracting direction whereby said label web may be retracted so that a label is at a pre-determined start position.
Other aspects and features of the invention will become apparent be reference to the following description in conjunction with the drawings.